Possible to change 4.6L rod bearings with engine in vehicle?

[jayton]

The low oil pressure switch tripped about a mile from home. Checked oil level and it was good, made it home with the engine stalling once, low oil pressure continued switching on and off, and the engine started to make more noises as I came into my driveway that fluctuated with the rpms regardless of whether there was a load on the engine nor if it was in neutral.

I changed the oil & filter, and put in a new oil pressure switch. The truck started up fine and idled fine. The oil pressure light was off for about 2 minutes while it was running. Then the light began to flicker and then stayed on solid. If I very lightly touched the accelerator, it would go back off. So the amount of pressure being pumped is way down. The regular everyday rattling noises seemed to get louder than usual.

I suspect oil pump, and it will be a couple of days before I will be able to obtain a real oil pressure gauge. By this time, I have already seen enough without the gauge to know that I have a real problem here. So I dropped the pan and this is what I found:

There is not a trace of sludge on the pickup tube, as I am pretty meticulous about oil changes. Only shiny metal flakes. Like silver glitter, very finely ground into a sandy dust. It does not seem to be magnetic, which I would guess to be bearing material.

Is it possible to change the rod bearings with the engine still in the vehicle? I do not currently have access to a cherry picker. I already have everything off the front of the engine, and will have the valve covers and timing cover pulled by tomorrow. I have the tools needed to easily drop the drive shaft and transmission as well as removing the flywheel to clear everything off of the back.

Would I be able to detect rod bearing damage by pulling main caps off the bottom and inspecting?

So far I have purchased or ordered the following for the job: Melling Oil Pump, Felpro timing cover gasket, Ford dealer crankshaft pulley bolt, the specialty Ford camshaft tools (OTC 6009 and 6020).

Every single thread on this topic on most forums seem to say to give up and swap engines from a junkyard or a remanufacturer. I do not have those kind of funds, as junk yard engines start around $2100 for the ones that don't say already broken or burnt. The rebuilt engines are in the range of $2800-3200. Racking up a ton of labor hours does not matter to a shadetree and I don't mind taking a big puzzle apart and then putting it back together. I am not in a panic or rush to get this done the quickest and easiest way possible. I have a backup car available and I need this to be done the cheapest way possible.

Are there any particular tips and tricks I should know about? What should I do about timing? Some things I read say put it at TDC and place the cam holders in. Others say line up the marks after turning the crank keyway to 12 o'clock so that the engine is in its "safe zone," where cams can be rotated freely without risk of valves touching pistons.

What else do I need on my shopping list? Timing chain guides? Front and rear oil seal?


Engine History:
-Currently has 185,006 miles, bought it in 2006 with 105,000 miles and up until recently, it has been the most trouble-free engine I have ever owned in my life.
-First problem was around 176,000 miles, 10 months ago. Hesitation on acceleration and idle, misfire codes on cyl 5 & 6. The valve cover gasket leaked oil in and gunked up the plugs. Cleaned it out, put in new plugs, boots, valve cover gaskets. All was well.
-Second problem was just 3 months ago in April when the rearward catalytic converter became clogged. I got a direct-fit replacement bolt-in y pipe and 3 cats from Eastern Catalytic to replace the factory unit. This thing looks like it was welded together by high school students completing there first class project in shop class. There are a couple of exhaust leaks in the new system. It is definitely the get-what-you-paid-for game when it comes to exhaust. If it ever happens again on a future vehicle, I'll hope I'll be able to afford the Magnaflow.

 

[2Trux]

Since you have the pan off and have access to the bottom of the engine you should be able to change the rod and main bearings. Looking at the main bearings will only show their damage, but if they are bad you can figure that the rod bearings need replacement.
The only downfall is if the crank journals are scored or damaged the crank will have to come out to be machined. This would be quite the trick to pull off without removing the engine.

 

[Javadog123]

If you were burning up your bearings, you might have damages your cylinder walls too. They may just need to be reamed and honed as opposed to bored out. If you are going to all the work to replace bearings, you might as will look. Especially if you end up pulling engine.

 

[swetrid]

If rod bearings are gone you will need crank serviced or it will come right back with same noise and oil pressure concerns. The worn bearings will wear into the crank surface.

 

[jayton]

Thanks for the replies!

I have one correction to make to my original post: the material in the oil pan is indeed magnetic. The first magnet tool I tried must not have been strong enough or it was all still drenched in oil.

I will be pulling the truck (pushing actually) into my garage so that I can work on this thing at night. Using lights outside gets my face covered in bugs.

 

[jayton]

If rod bearings are gone you will need crank serviced or it will come right back with same noise and oil pressure concerns. The worn bearings will wear into the crank surface.

I just got to where I could inspect the rod bearings today, and you were exactly right. There were two rod bearings that chewed up my crankshaft.

I'm now shopping for another engine to swap in.